@@ -2247,6 +2247,8 @@ static int tc_ctl_chain(struct sk_buff *skb, struct nlmsghdr *n,
err = -EINVAL;
goto errout_block;
}
+
+ mutex_lock(&block->lock);
chain = tcf_chain_lookup(block, chain_index);
if (n->nlmsg_type == RTM_NEWCHAIN) {
if (chain) {
@@ -2258,41 +2260,49 @@ static int tc_ctl_chain(struct sk_buff *skb, struct nlmsghdr *n,
} else {
NL_SET_ERR_MSG(extack, "Filter chain already exists");
err = -EEXIST;
- goto errout_block;
+ goto errout_block_locked;
}
} else {
if (!(n->nlmsg_flags & NLM_F_CREATE)) {
NL_SET_ERR_MSG(extack, "Need both RTM_NEWCHAIN and NLM_F_CREATE to create a new chain");
err = -ENOENT;
- goto errout_block;
+ goto errout_block_locked;
}
chain = tcf_chain_create(block, chain_index);
if (!chain) {
NL_SET_ERR_MSG(extack, "Failed to create filter chain");
err = -ENOMEM;
- goto errout_block;
+ goto errout_block_locked;
}
}
} else {
if (!chain || tcf_chain_held_by_acts_only(chain)) {
NL_SET_ERR_MSG(extack, "Cannot find specified filter chain");
err = -EINVAL;
- goto errout_block;
+ goto errout_block_locked;
}
tcf_chain_hold(chain);
}
+ if (n->nlmsg_type == RTM_NEWCHAIN) {
+ /* Modifying chain requires holding parent block lock. In case
+ * the chain was successfully added, take a reference to the
+ * chain. This ensures that an empty chain does not disappear at
+ * the end of this function.
+ */
+ tcf_chain_hold(chain);
+ chain->explicitly_created = true;
+ }
+ mutex_unlock(&block->lock);
+
switch (n->nlmsg_type) {
case RTM_NEWCHAIN:
err = tc_chain_tmplt_add(chain, net, tca, extack);
- if (err)
+ if (err) {
+ tcf_chain_put_explicitly_created(chain);
goto errout;
- /* In case the chain was successfully added, take a reference
- * to the chain. This ensures that an empty chain
- * does not disappear at the end of this function.
- */
- tcf_chain_hold(chain);
- chain->explicitly_created = true;
+ }
+
tc_chain_notify(chain, NULL, 0, NLM_F_CREATE | NLM_F_EXCL,
RTM_NEWCHAIN, false);
break;
@@ -2327,6 +2337,10 @@ static int tc_ctl_chain(struct sk_buff *skb, struct nlmsghdr *n,
/* Replay the request. */
goto replay;
return err;
+
+errout_block_locked:
+ mutex_unlock(&block->lock);
+ goto errout_block;
}
/* called with RTNL */
In order to remove dependency on rtnl lock, modify chain API to use block->lock to protect chain from concurrent modification. Rearrange tc_ctl_chain() code to call tcf_chain_hold() while holding block->lock to prevent concurrent chain removal. Signed-off-by: Vlad Buslov <vladbu@mellanox.com> --- net/sched/cls_api.c | 36 +++++++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 11 deletions(-)